1. Field of the Invention
The present invention relates to a ventilation member fixed to a housing for automobile electrical components or the like, and the housing to which the ventilation member is fixed.
2. Related Art
Ventilation members are attached to various housings of automobile electrical components such as ECUs (Electronic Control Units), lamps, motors, various sensors, pressure switches and actuators; cellular phones; cameras; electric shavers; electric toothbrushes; and lamps for outdoor use.
Each of the ventilation members prevents water or dust from invading the inside of a housing while playing various roles in accordance with the kind of housing to which the ventilation member is attached. The roles include propagation of voice, discharge of gas generated inside the housing, and relaxation of a change of pressure inside the housing caused by a change of temperature.
FIGS. 13A and 13B show an example of a related-art ventilation member. A ventilation member 51 shown in each of FIGS. 13A and 13B is used for an equipment housing to be exposed to contaminants such as rain, muddy water or oils, for example, for automobile electric components. The ventilation member 51 has an L-shaped or U-shaped (not shown) tubular body. The ventilation member 51 may have a structure having a maze 52 internally. One end of the ventilation member 51 is outer-fitted to a neck portion 50a provided in a housing 50 so that the ventilation member 51 is fixed to the housing.
FIGS. 14A and 14B show another example of a related-art ventilation member. In a ventilation member 60 shown in FIGS. 14A and 14B, a substantially cylindrical body 62 is fitted to the inside of a cover part 61 so as to form a ventilation path between the inner circumference of the cover part 61 and the outer circumference of the substantially cylindrical body 62 and between the bottom surface of the cover part 61 and the bottom portion of the substantially cylindrical body 62. When an opening in the bottom portion of the substantially cylindrical body 62 is covered with a filter 63, the ventilation member 60 can also exert a higher water-proofing property and a higher dust-proofing property (disclosed in Japanese Patent Laid-Open No. 2001-143524). An opening 62a in the top portion of the substantially cylindrical body 62 is outer-fitted to the neck portion 50a of the housing 50 so that the ventilation member 60 is fixed to the housing.
FIG. 15 shows another example of a related-art ventilation member. In a ventilation member 70 shown in FIG. 15, a tapered insertion portion 71a is formed in one end portion of a disc-like elastomer member 71, while a splash guard cover 71b is formed on the other end portion of the disc-like elastomer member 71, and a breathable film 72 is fixedly deposited on the way of a ventilation flow path penetrating between the one end portion and the outer circumference of the other end portion. A sealing/fixing portion 71c for fixedly retaining a housing 7 in cooperation with the insertion portion 71a is formed in the outer circumference of the elastomer member 71 (disclosed in Japanese Patent Laid-Open No. 85536/1998). The insertion portion 71a is pressed into the opening portion of the housing so that the ventilation member 70 is fixed to the housing.
However, the ventilation members have the following problems.
Each of the ventilation members 51 and 60 shown in FIGS. 13A and 13B and FIGS. 14A and 14B is fixed to the housing 50 only by outer fitting to the neck portion 50a of the housing 50. Therefore, there is a possibility that the ventilation member may be pulled out of the housing.
On the other hand, in the ventilation member 70 shown in FIG. 15, the surface abutting against the housing 7 is made of elastomer. Therefore, when oil invades a part of the surface of the ventilation member 70 abutting against the housing 7, it becomes easy to detach the ventilation member 70 from the housing. It cannot be therefore said that the ventilation member 70 is suitable as a ventilation member for a housing used in an environment easy for oil to adhere to the ventilation member.